seriously WTF

last month i received notification that i had just gone over my useage limit and phones support and asked for an increase in my bandwidth usage limit to cover the remaining days, couple of days later i recieved my monthly bill....... ><

Dear (personal details removed),
Please be advised, your invoice contains the following charges :

Monthly Broadband subscription - £29.35
48 GB monthly data transfer charge - £5.84
Included data transfer upgrade charge - £5.84
Total : £41.03

now the 48gb monthly data transfer charge i assumed was the charge for my increase in paid usage allowance

Monthly Broadband subscription - £29.35
48 GB monthly data transfer charge - £5.84
Included data transfer upgrade charge - £5.84 <-----------
Total : £41.03

"erm so in a sense your charging me twice for the same thing under differant names for me requesting my paid allowance to be upgraded from 40gb-48gb??"

Dear (persoanal details removed),
No (personal details removed), we are not charging you twice for the same thing. We charge an upgrade fee wwhen a customer adds on additional usage on the account. I can assure you the charges are correct.

pardon my language but wtf ?? waiting atm on a responce on this
so if the included data transfer upgrade charge is the charge for the increase then wtf are they trying to charge me under 48gb monthly data charge?

I believe that the first £5.84 is a payment in arrears for the current month when you went over your limit and requested additional capacity, and the second is a charge in advance for the same additional capacity for next month.